We know Colts running back Trent Richardson has talent -- we just haven't seen it in a while. After averaging 2.9 yards per carry last season following his trade from Cleveland, Richardson actually fared worse this preseason, gaining 51 yards on 20 totes (2.6 ypc).
Ahmad Bradshaw will eat into Richardson's touches and could supplant him if he keeps struggling. Coming off a neck injury, Bradshaw got his feet wet in the third preseason game, rushing three times for 2 yards and catching an 11-yard pass.
The Colts' offensive line is suspect. Indy bolstered its receiving corps and will rely more on Andrew Luck's passing this year. It's hard to envision a sudden Richardson revival.
If you start Richardson as your flex Sunday night at Denver, the best-case scenario is about 75 total yards and a short rushing score (he managed three rushing TDs last year). Not the most exciting way to start a Fantasy season.